THIS PRESENTATION ON CENTRELESS GRINDING REGARDING THE MANUFACTURING SUBJECT, THIS PPT PRESENTED AT B&B INSTITUTE OF TECHNOLOGY.
HOPE IT WILL HELPED THE ENGINEERING STUDENT.
2. OBJECTIVE
Definition of Centerless grinding.
Describe the relationship between the
three main components used in
cenerless grinding.
Describe advantages of centerless
grinding.
Describe the component of the
centerless grinding.
Describe how the regulating wheel
determines workpiece rotational speed.
Indentify Grinding wheel Imbalance
FIGURE 2.The regulating wheel is anglead slightly to
enable workpiece through feed.
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3. DEFINITION OF CENTERLESS GRINDING
Centerless grinding is a machining
process that uses abrasive cutting
to removal material from a
workpiece.
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4. CENTERLESS GRINDING.
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Common type of
Cylindrical grinding.
Three main parts are used.
i) Grinding wheel
ii) Regulating wheel
iii)Work Rest Blade
This component hold the work piece horizontally.
Rotate it & Grain its Surface.
Each component plays the roll in the grinding
process.
FIGURE: A Typical centerless grinding configuration
5. HOW THE CENTERLESS GRINDING WORKS.
The work rest blade supports
the part slightly.
It is made of wear-resistant
material.
The regulating wheel rotates the
Cylindrical parts.
It is commonly made of plastic
or rubber bond.
The actual grinding is performed
by Grinding wheel.
Both the wheel must be
periodically dressed and trued
to maintain precise roundness
of the workpiece
FIG. Shows a typical machine
built for Centerless Grinding. 5
6. The parts they Grind always must be round.
However, Setup is fast
And the process Can be automated.
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7. ADVANTAGES OF CENTERLESS GRINDING
It Enables Fast, accurate
production of complicated
hand-held parts or workpiece that
require Tight Tolerances.
Decrease grinding time.
Automatic Feeding method.
Reduce grinding wheel wear.
Grinding of longer parts.
Low Maintenance.
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FIGURE: center less grinding is often used to produse small Parts
such as bearings.
Centerless grinding is often used to mass production small parts
such as bolts , shafts, bearings, hubs or valves.
8. MAIN CATEGORIES OF CENTERLESS GRINDING.
Generally, all centerless grinder fall under two main
categories.
i) Angular-bed-grinders
ii)Horizontal-bed-grinders
On an angular-bed-grinder, the rotating regulating
wheel rotates the part @ specific rate .
Angular-bed-grinders are usually used to grind
heavier workpieces or workpieces that require a
fine surface finish.
The horizontal-bed centerless grinder is the most
common design.
The parts being to rotate only after it touches the
rotating grinding wheel.
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9. MAIN COMPONENT OF MACHINE.
A cast iron bed supports the
grinder and contains the
grinding and regulating wheel
head assembly and hydraulic
reservoir.
A wheel head contains the
grinding wheel and grinding
wheel spindle.
A swivel plate is mounted to
the bed and tilts or aling the
regulating wheel parallel to
the grinding wheel.
A lower slide is attached to
the swivel plate and moves
the regulating wheel and
workrest blade towards or
away from the workrest blade.
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FIG. The main component of centerless grinder
10. An upper slide is attached to the lower slide and
moves the regulating wheel towards or away from
the workrest blade.
A regulating wheel housing is mounted to the
upper slide and houses the regulating wheel
houses the regulating wheel and regulating wheel
spindle.
A work rest is mounted to the lower slide and
supports the work rest blade.
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11. THE REGULATING WHEEL & WORKPIECE
ROTATIONAL SPEED.
o During centerless grinding, the
Regulating wheel plays a key
role in the grinding of workpiece.
o Two key factors that the regulating
wheel controls are rotational
speed of the workpiece and the
feed rate of the workpiece.
o The surface speed of the
regulating wheel controls the
rotational speed, or work speed,
of the workpiece.
o During a centerless grinding
operation, the regulating wheel
rotates the workpiece by rotating
against it, as shown in fig.
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FIG: The regulating wheel rotates the workpiese
by revolving against it a uniform rate.
12. Surface speed is the uniform rate at which the
regulating wheel revolves against the workpiece.
Surface speed rate is measured in revolutions per
minute (RPM).
Most regulating wheel revolves between 30 and 40
rpm.
The work speed of the workpiece is approximately
equal to the regulating wheel surface speed.
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13. DETECTING GRINDING WHEEL IMBALANCE
A simple method for detecting
wheel imbalance is to take a wheel
that has been mounted on a
mandrel.
It is set between two equal points,
such as the balancing stand
shown in fig.
If the wheel stays at rest, even if it
rotated to a new position, it is said
to be static balance.
If the wheel is then pushed along
the stand, and it rotates smoothly,
stopping only when it loses
momentum, the wheel is said to be
in dynamic balance.
If the wheel is out of balance , it will
rock back and forth before coming
to rest with its heaviest side down. 13
FIG: Placing a grinding wheel on a balancing
stand will determine if one side is heavier than
another.